Computer systems have one or more processors that manipulate and control the flow of data by executing instructions. To provide more powerful computer systems, processor designers strive to continually increase the operating speed or frequency of the processor. As processor speed increases, the power consumed by the processor tends to increase as well resulting in higher temperatures within the processor. Moreover, increases in processor frequency and temperature can result in unreliable performance and cause errors to occur within the processor. Various techniques have been developed in an effort to optimally control processor temperature and frequency.
For example, some processors include an on-chip controller that adjusts the power supplied to the processor and the operating frequency of the processor based on a measured temperature of the processor. Thus, the processor can run at a higher operating frequency and, if the processor begins to overheat, the controller can reduce the processor's power and frequency until the processor's temperature falls back into a normal operating range. Therefore, the processor can achieve better performance during periods when its temperature is relatively low yet avoid at least some heat-related errors by throttling back power and frequency when the temperature increases above a specified threshold.
Moreover, the operating temperature and frequency of a processor can change while the processor is running. To ensure robustness, extensive testing of the processor is required. For example, before a processor manufacturer releases a product to the public, the manufacturer usually tests the processor at many different operating points to ensure that it operates correctly at the different operating points. As used herein, an “operating point” of a processor is defined by an operating frequency and temperature. Thus, if a processor is tested multiple times at the same operating point, then the processor's operating frequency and temperature are the same for each of the tests. However, if a processor is tested at different operating points for each of a set of tests, then the processor has a different operating temperature or frequency for each of the tests.
Based on the manufacturer's testing, the manufacturer typically configures a processor to operate within a certain range of operating points, referred to herein as the processor's “operating range.” The processor's on-chip controller, as described above, can be used in an effort to ensure that the processor operates only within its allowed operating range. However, despite the extensive testing performed on current processors, processor errors still occur even at operating points within the operating range specified by the manufacturer. Further, as a processor ages, the quality of hardware components typically degrades, and errors can become more frequent within the processor particularly at operating points close to the upper limits of its operating range.
Moreover, better techniques for reducing and handling processor errors are generally desirable.